1) Does the import alter the original threads database?
No, buts it is a good idea to close our old board for the import time.
2) If we wish to set up a test site, do we have to duplicate our existing threads database first?
No, you import from your old one to a new one (and this doubles the needet space in your db)
3) Does our licence allow for a public test site?
I m not 100% shure but I guess so.